The invention relates to a tol and an insert, preferably for turning. The tool comprises a shank whose head portion is provided with a projection in order to engage with a hole in an insert provided with cutting portions and support surfaces provided to force the lower face of the insert into abutment with the mainly planar upper face of the head portion. The support surfaces which are arranged on a reciprocable first unit, engage with recesses in at least one edge surface of the insert. The hole of the insert is slidably arranged about the projection in order to wedge up on it during a forward movement of the insert.
In known inserts for turning, for example a rhombical insert, the insert is positioned in an insert site such that two cutting edges are exposed outside the insert holder to make it possible to turn both right-handed and left-handed. This means that the distance between the tip of the insert and the support points of the insert against the insert site coresponds to approximately half the length of an insert edge. An insert edge length is thus the moment arm by which the cutting forces influence the insert site. In conventional inserts the support points in the insert site are deformed and displaced such that the positioning of a new insert is deteriorated. A defective depth is caused in the work piece, since the tip of the insert then in some cases describes a movement of an arc of a circle. Furthermore it is previously known to arrange a wedge device between a planar side surface on the insert and a projecting surface on the tool shank. the wedge device forces the insert forwardly against a pin, secured into the planar upper face of the shank and received by the center hole of the insert. The distance between the tip of the insert and the support points of the insert is large also in that type of tool.